Aberdeen was hit by a rash of five robberies on Friday and Saturday, four of them armed, the city's police reported.
A sixth robbery was committed Monday but not reported until Tuesday, police said Thursday.
No one was injured during any of the incidents.
"All of the robberies are still active cases," Aberdeen Police Lt. Fred Budnick said earlier this week. "The criminal investigators are trying to determine if any are related."
Budnick said the spate of crimes might just be a sign of the season.
"It is a little unusual but we do see occasionally at this time of the year a little uptick in that kind of activity, with people looking for cash for the holidays or whatever," he said.
"I don't remember it being this many cases last year, but going back through my career here, I do recall an increase in property crimes [in past years]," he said.
Police have identified some suspects but have made no arrests, he said. He would not say which of the cases have suspects.
It was hard to make suspect descriptions because many of the robbers covered their faces.
He reminded residents to be careful of their surroundings and stay in well-lit areas. He said police have also increased patrols in business districts.
The first robbery was at Cricket Wireless, on Beards Hill Road near Route 22, where a man entered at about 6:49 p.m. Friday, displayed a handgun and announced a robbery, Budnick said.
The man fled after getting an undisclosed amount of cash and was last seen running toward Bel Air Avenue. He was described only as wearing a gray hoodie, sunglasses and a scarf.
At 7:15 p.m. the same night, police responded to a reported armed robbery in the first block of East Bel Air Avenue.
A woman was walking with a friend when she was approached by two males, Budnick said. One of the men asked if the woman had any money and advised he had a weapon.
He then produced a small knife and grabbed her money.
The robbers are described as a Hispanic and a black man, both in their 20s.
At 10:52 p.m. Friday, a man walking on West Bel Air Avenue near the railroad tracks told police he was approached by two men who forcefully took the victim's wallet, then fled the area on foot.
Those robbers are described as a black man and white man, wearing dark coats and jeans.
Just several hours later, at about 1:45 a.m. on Saturday, police responded to the first block of Norman Avenue to investigate an armed robbery.
A man told police he was walking near McDonald's on South Philadelphia Boulevard when he was approached by two men, one of whom produced a handgun and robbed him of money.
The robbers fled on foot and are described as black men, one with a heavy build and wearing a gray hoodie and khaki pants and the other with a medium build and wearing a dark hoodie and blue jeans.
At about 4:21 p.m. that day, police responded to the 600 block of Holly Drive for a reported robbery of a pizza delivery driver.
The victim said that as he was taking pizza from his car, two men approached him. One produced a handgun and demanded money.
The victim complied, and one of the robbers rifled through his clothing to remove more money, Budnick said.
The suspects fled the area on foot and no detailed description of the two men was provided.
A sixth robbery also was committed Monday, although it was not reported until Tuesday, Budnick said Thursday.
A woman told police she was approached by two men near Getty Mart and the railroad tracks on West Bel Air Avenue at about 7:30 p.m. Monday.
The men produced a gun and took medicine from the woman. She did not report the incident until about 11:50 a.m. the next day because she said she "tried to handle it herself," however, leading police to think the suspects and victim may know each other, Budnick said.
No arrests or further suspect information had been made for the other robberies as of Thursday morning, Budnick said.
Anyone with information is asked to call Aberdeen Police Department, Criminal Investigation Section, 410-272-2121.